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I have a multi module maven project. Please find below the parent POM.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.rohit.patterns</groupId>
    <artifactId>design-patterns</artifactId>
    <version>1.0.1</version>
    <packaging>pom</packaging>

    <name>React.js Blank Project (from https://github.com/making/maven-reactjs-blank)</name>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <slf4j.version>1.7.21</slf4j.version>
        <logback.version>1.1.7</logback.version>
    </properties>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-antrun-plugin</artifactId>
                <version>1.8</version>
                <executions>
                    <execution>
                        <id>gulp</id>
                        <phase>generate-resources</phase>
                        <goals>
                            <goal>run</goal>
                        </goals>
                        <configuration>
                            <target>
                                <echo message="Gulp!" />
                                <exec executable="gulp">
                                    <arg value="build" />
                                </exec>
                            </target>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <artifactId>maven-resources-plugin</artifactId>
                <executions>
                    <execution>
                        <id>copy-resources</id>
                        <phase>generate-resources</phase>
                        <goals>
                            <goal>copy-resources</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${basedir}/target/classes/META-INF/resources</outputDirectory>
                            <resources>
                                <resource>
                                    <directory>dest</directory>
                                    <filtering>false</filtering>
                                </resource>
                            </resources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
    <modules>
        <module>cache</module>
    </modules>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>slf4j-api</artifactId>
                <version>${slf4j.version}</version>
            </dependency>
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-classic</artifactId>
                <version>${logback.version}</version>
            </dependency>
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-core</artifactId>
                <version>${logback.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

The child POM is as follows.

<?xml version="1.0"?>
<project
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
    xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.rohit.patterns</groupId>
        <artifactId>design-patterns</artifactId>
        <version>1.0.1</version>
    </parent>
    <groupId>com.rohit.patterns</groupId>
    <artifactId>cache</artifactId>
    <version>1.0.1</version>
    <name>cache</name>
    <url>http://maven.apache.org</url>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

I have declared Logging from slf4j in parent but no maven dependencies for the same is generated in eclipse hence I am unable to use logging in the code. Can anyone let me know what is wrong here.

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1 Answer 1

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Using <dependencyManagement> in a parent pom allows to set the usable dependencies by the child modules.
It is a good thing as it centralizes them and specifies one and only one version.
But to use them, child modules have to declare them in the <dependencies> tag of the <build> tag.

You could for example modify the child pom in this way :

<dependencies>
...
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-core</artifactId>    
    </dependency>
...
</dependencies>

If you consider that these dependencies should be added in any child modules, favor dependencies over dependencyManagement in the parent pom declaration :

<dependencies>
...      
  <dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>${slf4j.version}</version>
  </dependency>
  <dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>${logback.version}</version>
  </dependency>
  <dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-core</artifactId>
    <version>${logback.version}</version>
  </dependency>
...
</dependencies>

Now, you don't need to declare any of these in the child modules as these dependencies will be already included.

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